The methylation of cytosine in genomic DNA is a typical modification of epigenetics (epigenome) regulating gene expression. Possible regulation of the methylation of a particular gene enables elucidation of epigenome diseases such as cancer, production of models of the diseases, and its application to epigenome treatment. Currently, treatment of cancer using the demethylation of the whole genome with 5-azacytosine or the like is put into practical use. However, the treatment affects all genes, and therefore, some doubt remains as to safety concerns. Therefore, development of a technology for regulating the methylation of a particular site has been desired.
As such a technology for regulating the methylation of a particular site, a technology for demethylating a particular gene by using a protein obtained by fusing TALEN and the catalytic domain of TET1 which is an enzyme involved in demethylation has been previously reported (Non Patent Literature 1). However, it was very time-consuming due to use of TALEN, which is a genome editing technology of the previous-generation, and the degree of demethylation has not been very high.
Examples of new-generation genome editing methods include a method of using CRISPR/Cas (Non Patent Literature 2). Although use and application of an array in which plural peptide epitopes are linked, and scFv which is a single-chain antibody for signal amplification have been reported (Non Patent Literature 3) as a CRISPR/Cas genome editing method, the method has not been known to be applied to regulation of DNA methylation.